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Subject Author Date
Shebang line for modules? Steve Roscio 01-08-2008
Posted by Claudio Calvelli on January 9, 2008, 9:51 am
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> Not quite true. You can set the $^W variable directly.
>
> package MyPackage;
> use strict;
> local $^W = 1;
>
> Btw, by localizing it, warnings would not be enabled outside the
> package, right?

They would not even be enabled inside the package though. The "local" will
mean that $^W is one during the module initialization, but not when its
code is called later. For example:

------ TEST.pm -------
package TEST;

use strict;
local $^W = 1;

print "in TEST: $^W=$^W\n";

sub w {
print "in TEST:w(): $^W=$^W\n";
}

1;
----------------------

-------- test --------
#!/usr/bin/perl

use TEST;

TEST::w();
print "outside TEST: $^W=$^W\n";
----------------------

Now type "perl test" or your OS's equivalent and you get:

------ results -------
in TEST: $^W=1
in TEST::w(): $^W=0
outside TEST: $^W=0
----------------------

note how $^W is zero when TEST::w() is called.

You could add "local $^W = 1" at the start of every sub within your package,
but that would enable warnings in any subroutine called from it, even if it
is in another package, which is probably bad manners.

C.
--
Real email address: join('@', 'intercal', 'sdf.lonestar.org')
It helps the spam filter if you include the word CAMEL in the subject.

Posted by Gunnar Hjalmarsson on January 9, 2008, 6:10 pm
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 Claudio Calvelli wrote:
>> You can set the $^W variable directly.
>>
>> package MyPackage;
>> use strict;
>> local $^W = 1;
>>
>> Btw, by localizing it, warnings would not be enabled outside the
>> package, right?
>
> They would not even be enabled inside the package though. The "local" will
> mean that $^W is one during the module initialization, but not when its
> code is called later.

Which wouldn't have been necessary to point out, if you hadn't snipped
my next sentence ("... only catch compile time warnings"). :(

> You could add "local $^W = 1" at the start of every sub within your package,

Those subs that are intended to be called from outside the package would do.

> but that would enable warnings in any subroutine called from it, even if it
> is in another package, which is probably bad manners.

That's a philosophical aspect on which I for one have no firm opinion. ;-)

--
Gunnar Hjalmarsson
Email: http://www.gunnar.cc/cgi-bin/contact.pl

Posted by Claudio Calvelli on January 10, 2008, 3:50 am
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> Claudio Calvelli wrote:
> Which wouldn't have been necessary to point out, if you hadn't snipped
> my next sentence ("... only catch compile time warnings"). :(

Sorry about that - I failed completely to even see it.
Now, if newsreader software could have a "warning: posting before
full caffeination" this wouldn't happen.

C
--
Real email address: join('@', 'intercal', 'sdf.lonestar.org')
It helps the spam filter if you include the word CAMEL in the subject.

Posted by Peter Scott on January 9, 2008, 10:25 am
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On Tue, 08 Jan 2008 14:31:51 -0700, Steve Roscio wrote:
> Does it makes sense to include a shebang line at the top of a .pm file?

Maybe:

        http://www.ddj.com/web-development/184416165

--
Peter Scott
http://www.perlmedic.com/
http://www.perldebugged.com/


Posted by Steve Roscio on January 9, 2008, 4:21 pm
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Thanx everyone! In my case it was a "stylistic" question, I had
wondered what was the defacto convention. I changed all my stuff
to 'use warnings' since that suited.

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